Grinding machine



May 31, 1938. c. H. RICHARDS I 2,119,290

' GRINDING MACHINE Filed Dec. 21. 1936 4 Sheet s-She et 1 y 1,193s. c. H. RICHARDS I 2,119,290

GRINDING MACHINE Filed Dec. 21, 1936 4 Sheets-Sheet 2 works Effie/B42 35 May 31, 1938. c, mc s 2,119,290

GRINDING MACHINE Filed Dec. 21. 1936 I 4 Sheets-Sheet 3 a UMrJesHJRb/kafia Patented May 31, 1938 v UNITED STATES PATENT OFFICE GRINDING MACHINE Charles H. Richards, Worcester, Mass., assignor to The Heald Machine Company, Worcester, Mass., a corporation of Massachusetts Application December 21, 1936 Serial No. 116,850

20 Claims.

The present invention relates to grinding manormally given a crossfeed movement relative to till til

the workpiece to bring the wheel and workpiece into grinding'contact, and thereafter to procure successively deeper and deeper cuts in the workpiece until the latter reaches the desired finished size.

In internal grinding machines, it is essential that the workpiece and the grinding wheel at the beginning of the grinding operation be positioned transversely of the machine relative to each other, so that the grinding wheel may enter the bore of the workpiece when either the wheel or the workpiece is given an axial movement. The wheel is subsequently moved transversely to bring thegrinding wheel and workpiece into grinding contact, and for reducing the inoperative time of each grinding operation, this crossfeed movement must take place as rapidly as possible. One of the principal objects of the present invention is to provide for a rapid crossfeed movement with a provision for reducing the rate of crossfeed movement immediately upon engagement between the wheel and workpiece'independently of the unfinished size of the workpiece.

In a copending application filed by Schmidt and Blood, Serial No. 68,291, filed March 11, 1936, is disclosed a structure by which the rate of cross feed movement is reduced upon engagement between the wheel and the workpiece, and this structure incorporates a grinding wheel which is a conductor of electricity and forms part of a circuit which is closed upon engagement between the wheel and the workpiece. This arrangement is entirely satisfactory in operation, but there are occasions when such an arrangement is not desirable, either by reason of the type of workpiece, the latter not being a conductor, or where the coolant forms such an insulation that a suitable necessity for having a wheel or a workpiece which.

is an electrical conductor.

The present invention accordingly incorporates an alternative mechanism for accomplishing the same result as in the Schmidt and Blood applicatime above referred to. In the presentinveutlon.

the rate of crossfeed movement is reduced as the result of the spring in the spindle carrying the grinding wheeLand the arrangement is such that a very small amount of spindle spring is necessary for procuring the reduction in the rate of crossfeed movement.

Other and further objects and advantages of the invention will more fully appear from the the line 3-3 of Fig. 2.

Fig. 4 is a vertical section substantially along the line 4-4 of Fig. 3, with parts broken away to show the crossfeed mechanism more clearly.

, Fig. 5 is a plan view of a part of the crossfeed mechanism.

Fig. 6 is a fluid pressure diagram.

Fig- 7 is a wiring diagram.

Like reference characters refer to like parts in the diflerent figures.

Referring first to Fig. 1, the machine has the usual reciprocatory table I provided in an internal grinding machine; either the grinding wheel or the workpiece to be ground is carried on said table, the reciprocations o! the latter operating in either case to produce a relative translatory movement between the wheel and the workpiece. In the construction shown, the table supports and carries a workhead 2 andrthe wheel new 3 is mounted on a bridge 4 which spans the guideways 5, Fig. 3, provided by the base i of the machine for the movements of the table- I. The grinding wheel I is carried on a spindle 8 journalled in the wheelhead 3, and is suitably rotated at a high rate of speed by any well known mechanism, which, in the present instance, consists of a motor, not shown, in the base of the machine, connected by a belt, also not shown, to a pulley 9, Fig. 7, onthe spindle.

The workpiece 11, Figs. 1 and 2, is mounted in a suitable work supporting structure which may be in the form of a chuck l0 carried on a spindle ll journalled in the workhead. The chuck is preferably driven at a relatively slow rate of speed from a motor it connected to the spindle it by a belt It. The clutch mechanism ll, of any well known construction, provides for stopping the rotation of the chuck without interfering with the operation of the motor I2. The clutch mechanism is under the control of a handle I! easily accessible to the operator of the machine.

The reciprocations of the table I to cause the desired relative traverse between the rotating grinding wheel and the work supporting structure are imparted in any well known manner, as

by the use of fluid pressure controlling and reversing mechanism, one type of which is described in the Blood and Burns Patent No.

" 2,011,105, dated August 20, 1935. It is sufficient blocks l8 and I9 adjustably mounted on the front of the table I and adapted alternately to engage and move a reversing lever 28. The reversing lever is connected by suitable mechanism to -a reversing valve 2|, Fig. 6. The reversing lever during the grinding operation, when the grinding wheel is within the bore of the workpiece, is so located as to be engaged alternately by the reversing dogs.

Referring now to Fig. 6, the pump 22, driven by a motor 23, directs fluid under pressure from a tank 24 through a pipe 25 to a casing 26 in which the reversing valve 2! is positioned. The casing 26 has an inlet port 21 to which the pipe 25 is connected, and also has spaced outlet ports 28 and 23 connected by pipes 30 and 3i, respectively, to the'left and right hand ends of a cylinder 32 mounted in the base of the machine. A piston 33, slidable in the cylinder, has a piston rod 34 connected to a depending ing 35 on the table i. The reversing valve alternately directs fluid under pressure from the inlet port 21 to the outlet ports 28 and 29 and, at the same time, connects the opposite outlet port to an exhaust port 36 suitably connected to the tank.

The crossfeed movement'between the workpiece and the grinding wheel is obtained by transverse movement of the wheelhead 3 on the brid e 4. Movement of the cross-slide 31, Fig. 3, on which the wheelhead is mounted, is efiected by rotation of the crossfeed screw 38, which is held against endwise movement by anti-friction bearings 39 engageable with the rearward end thereof. The crossfeed screw engages an internally threaded portion 46 of the cross-slide for effecting the transverse movement thereof. On the forward end of the crossfeed screw 38 is mounted a gear 4! which meshes with a pinion 42 secured against turning movement on a shaft 43 journalled in a housing 44 for the crossfeed mechanism. Also secured to the shaft 43 in spaced relation to the gear 42 is a ratchet wheel 45 engageable by spaced oppositely directed pawls 46 and 41, Fig. 4, carried by an annular member 48 secured against turning movement on a sleeve 49 journalled on the shaft 43. The sleeve 49 has an integral pinion 53 engageable by a rack 5| horizontally slidablein the casing 44, said rack being held in engagement with the pinion by a bearing 52. The rack 5| is shifted by a fluid pressure mechanism, hereinafter described in detail, and procures through the pawl and ratchet arrangement a rotation of the shaft 43, and accordingly a rotation of the crossfeed screw. Manual rotation of the crossfeed screw is by a hand wheel 43 on the end of the shaft 43.

The pawl and ratchet arrangement is fully described in the Guild Patent No. 1,971,138, dated. August 21, 1934. It is sufficient to note for the purpose of the present application that this double pawl arrangement permits, during the return of the crossfeed slide to original position in readiness for a subsequent grinding operation, a com.

pensation for the reduction in size of the grinding wheel as a result of wear and the dressing operation performed thereon during the preceding grinding operation. With reference again to Figs. .3 and 4, it will be noted that both of the pawls are normally held in operative engagement with the ratchet by a spring 53, so that a rotation of the annular member 48 provides a corresponding rotation of the ratchet 45. The pawl 41 is operative during the crossfeed movement, and the pawl 46 is operative during the retraction of the crossfeed movement, the latter involving a counterclockwise rotation of the member 48. The pawl 46 is rendered inoperative during a part of the movement of the annular member 48 in the counterclockwise direction, so that the cross-slide is retracted a slightly shorter distance than it is moved forward during the crossfeed movement.

To effect this compensatory movement, the shaft 43 has journalled thereon an arm 54 having a gear segment 55 on the outer end thereof. The gear segment engages with a pinion 56 on a shaft 51 journalled in the front wall of the housing 44. The outer end of the shaft 51 has a knurled knob 58 by which said shaft is turned for shifting the position of the arm 54. Integral with the arm 54 is a cam 53 in a position for engagement with a pin 60 on the pawl 46 just before the termination of the crossfeed movement. Thus during the first part of the retraction of the crossfeed movement, the pawl 46 is inoperative and a rotation of the annular member 48 procures no corresponding movement of the ratchet wheel until the pawl 46 is released by the 'cam 59. During the remainder of the counterclockwise movement of the member 48, the retraction of the crossfeed movement takes place.

Referring now to Figs. 4 and 6, the rack 5! is carried on the end of a piston rod 69, extending from a piston 62 slidable in a horizontally positioned cylinder 63 mounted on the front of the bridge. Fluid under pressure is directed alternately to opposite ends of the cylinder 63, for procuring a crossfeed movement and the retraction thereof. As shown in Fig. 6, fluid under pressure from the pipe 25 passes through a pipe 64 to the inletport 65 of a reversing valve casing 66 for a reversing valve 61 for the crossfeed mechanism. An outlet port 68 in the casing is connected by a pipe 68 to the left hand end of the cylinder 63, and a port 10 is connected by a pipe 1| and suitable valve mechanisms, hereinafter described, to the right hand end of the cylinder. An exhaust port 12 for the reversing valve casing provides for exhaust of fluid from the end of the cylinder, and this port is suitably connected to the tank 24.

The admission of fluid to the right hand end of the cylinder 63 from the valve 61 is controlled by a horizontally slidable valve 13 positioned in a casing 14 mounted above the cylinder 63. The

pipe 1|, in which is positioned a main throttlevalve 15, is connected to a channel 16 in the block 11 in which the valve casing 14 is positioned. A channel 18 intersects the channel 16 and provides a direct connection to a port 19 in the casing 14. A transverse channel 60, also intersecting the channel 16, provides a connection from said channel to spaced vertically positioned valves 8| and 82 in the block 11. The valve 8| is a rough feed valve which controls the rate of crossfeed movement during the first part of the grinding operation, and the fine feed valve 82 controls the rate of crossfeed movement during the latter part of the grinding operation.

A channel 83, Fig. 4, in the casing 14 and the block 11, and an intersecting channel 84 in the cylinder 83, provide a fluid connection from the valve 13 to the right hand end of the cylinder. With the valve 13 in theposition shown, fluid under pressure from the pump under the control of the throttle valve 15 passes around a reduced portion 85 of the valve 13 to enter the right hand end of the cylinder, thereby procuring a rapid crossfeed movement of the grinding wheel to bring the grinding wheel and workpiece into engagement. When the grinding wheel and workpiece engage each other, the valve 13 is shifted to the right, by mechanism hereinafter described, to cut off the fluid connection provided by the reduced portion 85 of the valve and provide fluid connection around a reduced portion 88 of the valve from a channel 81 in the casing 14 connecting to the end of the valve 8|. After the movement of the valve 13 as above, the rate of crossfeed movement is under the control of the has valve 8I for a rough grinding operation.

Movement to the left of the valve 13 which at the beginning of the machine operation is nor mally held in the position of Figs. 4 and 6, is limited by mechanism best shown in Figs. 4 and 5. Referring to Fig. 4, a cap 88 on the block 11 has a plunger 88 slidable therein in line with and at the left hand end of the valve 13. Movement of the plunger to the left beyond the position of Fig. 4 is limited by a ring 88 on the cap 88 and a coil spring 8I positioned in a recess 82 in the casing 14 engages with the right hand end of a full-size portion 83 of the valve 13 to hold the valve against the plunger. The plunger carries on its left hand end a roller 84 engageable during the crossfeed movement with a cam 85 carried by the annular member 48.

The valve 13 is shifted to the right when the grinding wheel engages theworkpiece by means of a lever 88, Fig. 5, pivoted on a pin 81 extending from a part of the block 11. One end of the lever 86 is connected by a pin 88 to the projecting stem 88 ofthe valve 13, this stem having a slot I88 in which the pin 88 isslidable to provide'a iost-motion connection. The opposite end of the lever 86 is connected to the armature I8I of a solenoid I82 which is' energized by structure hereinafter described at the instantthat the grinding wheel engages the workpiece during the crossfeed movement.

The structure above described is similar to structure already disclosed and claimed in prior patents and pending applications and is not, of itself, the present invention. The latter involves the attainment, in connection with the above, or similar grinding machine structure, of the objects and novel features above set forth. accordance with the present invention the spring of the grinding wheel spindle, resulting from the pressure between the wheel and the workpiece established by the crossfeed movement, is used to procure a change in grinding operation, which. in the present instance, is the reduction in the rate of crossfeed movement above referred to, when the rough feed valve 8| becomes operative.

With reference to the wiring diagram of Fig. '7,

, wheel engages the workpiece.

one terminal -of the solenoid I82 is connected by a lead I83 to a metallic cup I84 filled with a conducting fluid I85, such as mercury. The other terminal of the solenoid is connected by a lead I86 to a source of direct current power represented by the parallel leads I81 and I88. The other lead I88 is connected to a micro-ammeter 388 having an indicating needle II8, the end of which is in a position to engage with the cup of conducting fluid I85.

A source of alternating current is represented by the transformer III and one terminal of the secondary winding of this transformer is connected by a lead II2 connected to two opposed primary windings H3 and II 4 oppositely wound on a magnetic core I I5 having a secondary winding II6.' The terminals of this secondary winding I IB are connected by leads H1 and H8 to opposite terminals of a suitable bridge rectifier II8 of familiar construction. The other terminals of this rectifier are connected by leads I28 and I2I to a coil I22 forming a part of the micro-ammeter I88.

The opposed primary windings H3 and H4 form two arms of a Wheatstone bridge, and the other two arms consist of two coils I23 and I24 adjustably positioned inside ofa casing I25 on the front of the wheelhead 3i (see Fig. 2). One

terminal of each of the coils I23 and I24 is con-" mature has a diamond point I 28 engaging with the grinding wheel spindle at a point diametrically opposite to the point where the grinding The movements of the armature I21 may be limited by adjustable screws I28 and I38 in the casing I25.

It is apparent that when the armature I21is in its normal position midway between the coils I23 and I24, as shown in Fig. '7, the Wheatstone bridge will balance, the currents in the primary windings H3 and H4 will be equal, and no voltage will be induced in the secondary winding H8. When the armature 131 is moved forwardly by the spring in the grinding wheel spindle as the 'wheel engages the workpiece the Wheatstone bridge will become unbalanced, inducing a voltage in the secondary winding I I8, and causing a rocking movement of the indicating needle II8 to close the circuit through the solenoid I 82. The spring in the grinding wheel spindle is set up immediately upon engagement between the wheel and the work and the arrangement is such that only an infinitesimal amount of spindle spring is necessary to procure energization of the solenoid I82, so'that the latter is energized almost immediately upon contact between the wheel and the workpiece.

With the solenoid I 82 energized, the valve 13 is shifted to the right, establishing fluid connection through the rough pr coarse feed valve 8| to the right hand end of the cylinder 83, so that the grinding operation continues with the wheel moving at the roughing speed, which is a materially slower rate of speed than during the inoperative period when the grinding wheel and workpiece are approaching each other'but not in engagement.

Subsequent to the slow-down of the crossfeed movement for rough grinding, above described, the cam 85 approaches and ultimately engages the roller 84 toshift the valve 13 further to the right, cutting oil the flow of fluid through the coarse feed valve-8| and establishing a flow of fluid through the fine feed valve 82, the fluid at this time passing around a reduced portion I3I of the valve 13 to-a channel I32 communicating with the channel 84, and the grinding operation is completed with the crossfeed movement occurring atan extremely slow rate.

The grinding operation may be brought to a close by any suitable mechanism, as for example, the mechanism fully disclosed in the Blood and Burns Patent #2,0ll,'705, dated August 20, 1935. Whatever the type of size-controlling mechanism used, the grinding wheel and workpiece are axially separated at the completion of the grinding operation by rendering inoperative the reversing dog II. Simultaneously the valve 6! is shifted by suitable mechanism, not shown, into the position of Fig. 6, thereby directing fluid under pressure to the left hand end of the cylinder 63 for movement of the piston 62 to the right. At this time fluid under pressure from the left hand end of the cylinder 63 passes through a channel I33, Fig. 6, connecting the cylinder to the left hand end of the valve 13 between said valve and the plunger 89. Fluid under pressure at the end of the valve I3 shifts said valve still further to the right to uncover an exhaust port I34 in the casing 14 and block II to allow fluid from the right hand end of the cylinder 63 to exhaust through the channels 84 and I32 and around a reduced portion I35 of the valve" to the port I 34. The port I34 is connected by suitable piping to the tank.

As the table moves to the left to rest or loading position, a cam I36, Fig. 1, carried by the table engages with the actuator I31 of a switch I33, Fig. 7, thereby opening the circuit through the solenoid I02 to allow the needle IIII to return to the position of Fig. 7 in readiness for a subsequent grinding operation. The switch is located in the circuit through the coil I I6, and may be in the lead I I8, as shown.

The operation of the machine so far as it is applicable to the present invention will be briefly summarized. With the machine in the position of Fig. l, and with a workpiece a positioned in the chuck III, the handle I5 is shifted to cause rotation of the workpiece. Movement of the table to the right to bring the workpiece and grinding wheel into operative position is then procured by movement of the ,lever I39, Fig. 1, which is suitably connected to the table reversing valve 2I. As the table reaches operative grinding position the valve 61 is shifted from the position shown by any suitable mechanism, preferably in response to the table movement, to direct fluid under pressure into the right hand end of the cylinder 63.

At the beginning of the crossfeed movement the valve I3 being in the position shown, fluid under pressure enters the cylinder 53 through the channels I8 and 19 and around the portion 35, so that the rate of crossfeed movement is under the control of the main throttle valve I5. Thus the cross slide moves at maximum speed until the grinding wheel has been advanced laterally, "relative to the workpiece; from the position of Fig. 3, into engagement with the bore of the workpiece. when the grinding wheel engages the workpiece b'ore, pressure exerted by the wheel against the workpiece causes sufilcient spring in thegrinding wheel spindle 8 to cause the solenoid. N12 to be energized, thereby shifting the valve I3 to the right for materially reducing the rate of crossfeed movement.

After the reduction of crossfeed movement the grinding-operation continues in the usual manner until the grinding operation is brought to a close by an extended movement of the table to the left. When this occurs the switch I33 is opened, thereby breaking the circuit through the winding II 5 to open the direct current circuit through the solenoid I02 and allow the valve I3 to be returned to its original position under the action of spring 9| in readiness for a subsequent grinding operation.

It will be apparent that the solenoid I02 is energized by a movement of the wheel spindle 8, at the point where it is engaged by the diamond point I28, relative to the casing I25. Although this movement of the spindle is generally caused by the spindle spring resulting from contact between the wheel and the work, it is apparent that a similar movement may result by reason of the type of bearing mounting for the spindle, since the necessary amount of spindle movement is extremely small. Thus the solenoid is energized by a movement of the wheel spindle relative to the wheelhead or to the casing I25, whether such movement results from spindle spring or otherwise.

From the foregoing it will be apparent that the invention provides for a change in the grinding operation in response to a movement of the wheel spindle relative to the wheelhead or other parts of the machine, resulting from engagement between the grinding wheel and the workpiece. This relative movement may be effected by a springing of the wheel spindle. One change in the grinding operation may be, as above disclosed, a reduction in the rate of cross feed movement, which can be arranged to take place immediately upon contact between the grinding wheel and the workpiece during the crossfeed movement. By this arrangement the reduction in the rate of the crossfeed movement will take place independently of variations in the unfinished diameters of successive workpieces, and the device is accordingly operative in the successive grinding of a plurality of workpieces which vary substantially in unfinished diameter.

I claim:

1. In a grinding machine, a grinding wheel spindle having a grinding wheel thereon, a worksupporting means, means for procuring a crossfeed movement between the wheel and a workpiece in the work-supporting means, means for controlling the rate of crossfeed movement, and means responsive to movement of the wheel spindle relative to the supporting structure by reason of the spring set up in the wheel spindle by engagement between the wheel and workpiece in the work-supporting means for actuating said controlling means.

2. In a grinding machine, a. grinding wheel spindle having a grinding wheel thereon, a worksupporting means, means for procuring a crossfeed movement between the wheel and a workpiece in the work-supporting means, means for changing the rate of crossfeed movement,'means operative upon engagemenfbetween "the wheel and the workpiece and in response to movement of the spindle relative to the supporting structure by reason of the spring set up in the wheel spindle by said engagement for actuating said changing means.

3. In a grinding machine, a work-supporting member having the workpiece therein, a wheelhead, a spindle joumalled in the wheel head and having aprojecting end on which a grinding wheel is mounted, means for procuring a relative movement between the wheel and the workpiece for bringing the wheel and workpiece into engagement, and means operative upon engagement between the wheel and the workpiece and actuated by movement of the spindle relative to the wheelhead by reason of the spring set up in the wheel tive movement between the wheel and the workpiece for bringing the wheel and workpiece into engagement, and means operative upon engagement between the wheel and the workpiece and actuated by movement of the spindle relative to the wheelhead by reason of the spring set up in the wheel spindle for reducing the rate of relative movement.

.5. In a grinding machine,-a grinding wheel spindle having a grinding wheel thereon, a worksupporting means having a work-piece therein,

means for procuring a relative movement between the wheel and workpiece for bringing the wheel and work into engagement, and means for procuring a change in the machine operation upon engagement between the wheel and the workpiece, said change procuring means being actuated by movement of the spindle relative .to the wheelhead by reason of the spring set up in the spindle as a result of engagement between the wheel and the work.

6. In a grinding machine, "a work-supporting member, a wheelhead, a spindle journalled in the wheelhead and having a grinding wheel mounted thereon, means for procuring a relative movement between the wheel and a workpiece in the work-supporting member, and means actuated by movement of the wheel spindle rela: tive to the wheeihead resulting from engagement between the wheel and the workpiece for procuring a change in the machine operation.

7. In a grinding machine, a work-supporting member, a wheelhead, a spindle journalled in the wheelhead and having a grinding wheel mounted thereon, means for procuring a rela- -tive movement between the wheel and a workpiece in the work-supporting member, a feeler engageable with the wheel spindle at a point substantially opposite to the line of contact between the wheel and the workpiece, and means responsive to movement of the feeler for changing the rate of relative movement between said wheel and workpiece.

8. In a grinding machine, a grinding wheel spindle having a. wheel thereon, a work-support having a workpiece therein, hydraulically actuated means for procuring a feeding movement between the wheel and the workpiece, a valve controlling the admission of fluid to said feeding means, a solenoid for shifting said valve, 9. feeler engageable with the wheel spindle at a point substantially opposite to the line of contact between the wheel and workpiece, and means responsive to movement of said feeler for closing a circuit through the solenoid. 1

9. In a grinding machine, a grinding wheel spindle having a wheel thereon, a work-support having a workpiece therein, hydraulically actuated means for procuring a crossfeed movement between the wheel and the workpiece, a valve controlling the admission'of fluid to said crossfeed means, a solenoid for shifting said valve, a feeler engageable with the wheel spindle, and means responsive to movement of said feeler when the wheel engages the workpiece for closing a circuit through the solenoid and thereby procuring a reduction in the rate of crossfeed movement.

10. In a grinding machine, a grinding wheel spindle havinga wheel thereon, a work-support having a workpiece therein, hydraulically actuated means for procuring a crossfeed movement between the wheelfand the'workpiece, a valve controlling the admission of fluid to said crossfeed means, a feeler engageable with the wheel spindle at a point substantially opposite to the line of contact between the wheel, and workpiece, and means responsive to movement of the feeler for shifting said valve.

11. In a grinding machine, a wheel supporting member having a wheel thereon, a work-supporting member having a workpiece mounted therein, means for procuring a relative movement between said members, means responsive toengagement between the wheel and the workpiece for providing a shifting movement of one of said members relative to the supporting structure therefor, means for procuring a change in the rate of relative movement between said members, a' solenoid for actuating said last means, and means for energizing the solenoid, said means including a normally balanced circuit, and means for unbalancing the circuit to energize the solenoid in response to said shifting movement.

12. In a grinding machine, a wheel supporting member having a wheel thereon, a work-supporting member having a workpiece mounted therein, means for procuring a. relative movement between said members, means responsive to engagement between the wheel and the workpiece for providing a shifting movement of one of said members relative to the supporting structure therefor, means for procuring a change in the rate of relative movement between said members, a solenoidfor actuating said last means, and

means for energizing the solenoid, said means therein, means for procuring a relative movement between said members to bring the wheel and workpiece into engagement, means for supporting one of the members for shifting movement relative to its supporting structure in response to-engagement between the wheel and workpiece, an armature movable in response to said shifting movement, a coil carried by the supporting structure and relative to which the armature is movable, a circuit including said coil, a solenoid adapted to be energized by a change in the circuit resulting from movement of the armature relative to the coil, and means controlled by said solenoid for procuring a change in the relative movement between the members.

14. In a grinding machine, a wheel supporting member having a wheel thereon, a worksupporting member having a workpiece mounted therein, hydraulically actuated means for procuring a relative movement between said members to bring the wheel and workpiece into engagement, means for supporting one of the members for shifting movement relative to its supporting structure in response to engagement between the wheel. and workpiece, an armature movable in response tosaid shifting movement, a coil carried by the supporting structure and relax tive to which the armature is movable, a circuit including said coil, a solenoid adapted to be energized by a change in the circuit resulting from movement of the armature relative to the coil, and a valve controlled by said solenoid for procuring a change in the relative movement between the members.

15. In a grinding machine, a wheel supporting member having a wheel. thereon, a worksupporting member having a work-piece mounted therein, means for procuring a relative movement between said members, one of said members being supported for shifting movement relative to the supporting structure when the wheel engages the workpiece, and means responsive to said shifting movement for procuring a change in the machine operation.

16. In a grinding machine, a wheel supporting memberhaving a wheel thereon, a work-supporting member having a workpiece mounted therein, means for procuring a relative movement between said members, one ofsaid members being mounted for shifting movement relative to the supporting structure when the wheel engages the workpiece, and means responsive to said shifting movement for procuring a change in the rate of said first relative movement.

17. In a grindingmachine, a wheel supporting member having a wheel thereon, a work-supporting member having a workpiece mounted therein, means for procuring arelative movement'between said members, one of said members being mounted for shifting movement relative to the supporting structure when the wheel engages the workpiece, and means responsive to said shifting movement for procuring a reduction in the rate of relative movement between the members.

18. In a grinding machine, a wheel supporting member having a wheel thereon, a work-supporting member having a workpiece mounted therein, hydraulically actuated means for procuring a relative movement between said members, one of said members being mounted for shifting movement relative to the supporting structure when the wheel engages the workpiece, and a valve movable in response to said shifting movement for procuring a change in said first "relative movement.

19. In a grinding machine, a spindle having a grinding wheel thereon, a work-supporting means, means for procuring a feeding movement between the wheel and a workpiece in the worksupporting means, a wheelhead in which the spindle is journalled, a feeler mounted on the wheelhead and engageable with the spindle for movement by the spindle when the latter is shifted relative to the wheelhead by engagement between the wheel and the workpiece, and means under the control of said feeler for procuring a change in the machine operation.

20. In a grinding machine, a spindle having a grinding wheel thereon, means, means for procuring a feeding movement between the wheel and a workpiece in the worksupporting means, a wheelhead in which the spindle is journalled, a feeler mounted on the wheelhead and engageable with the spindle for movement by the spindle when the latter is shifted relative to the wheelhead by engagement between the wheel and the workpiece, and means under the control of said feeler for procuring a change in the rate of feeding movement between the wheel and the workpiece.

CHARLES H. RICHARDS.

a work-supporting 

